Insect Bytes for April 15, 2017
Posted: April 14, 2017
Similarly to plants, the complex of early season insect pests are also active and require attention. The 2017 biofix for redbanded leafroller (RBLR) was established on March 30th, spotted tentiform leafminer (STLM) on April 01st and Oriental fruit moth (OFM) on April 05th. Although the biofixes for codling moth (CM) or tufted apple budmoth (TABM)are usually aligned with the full bloom on apples, the development of trees during this season appears to progress faster then accumulation of degree days needed for the cessation of diapause and the beginning of flights for CM and TABM.
Based on the heat unit accumulations called degree days (DD) we expect the flights of CM and TABM to begin within the next two weeks. The easiest and most economical way to detect the beginning of flight for most orchard pests and then continuous monitoring of pest activities is to use pheromone traps. Pheromone traps for monitoring oriental fruit moth, codling moth, tufted apple budmoth, and even brown marmorated stink bug should be already placed in orchards. Properly maintained monitoring traps will not only tell us if the pests are present in orchards but also help to decide if and when management activities are needed. The seasonal insect pest trapping updates for the Penn State Fruit Research and Extension Center (FREC) orchards are posted at the web site.
Oriental fruit moth
Oriental fruit moth biofix was established on April 05th, matching the earliest ever biofix date for this species from the 2012 season. During this past week, the traps baited with the OFM sex pheromone lures and located in our experimental orchards at the PSU FREC in Biglerville, PA on average collected more than 200 OFM males per trap. According to the OFM egg hatch model provided by the SkyBit program, the five percent egg hatch of OFM is expected to occur around April 19th and about 15 percent OFM egg hatch is expected by April 24th.
While those potential management timings should align well with the expected petal fall in peach and nectarine orchards, apple orchards will most likely still be in full bloom. No insecticides should be used while bees are still present and actively foraging in orchards. If needed, the petal fall insecticide treatment on peaches in addition to OFM should also be directed against plum curculio, stink bugs and tarnished plant bug. An application of Assail® or Avaunt® should provide good control of all species in this group of pests and Assail will also provide effective control of aphids present in peach orchards.
Photo 1. Left to Right; Delta style Oriental fruit moth monitoring trap (Pherocon VI) in peach orchard, OFM males inside the trap, and peach terminal injured by OFM larvae. Photos: G. Krawczyk
The pear psylla adult populations appear to be at relatively low levels comparing to previous years. During our last week field observations, despite not applying any treatments directed against pear psylla, we did not find too many nymphs or eggs normally abundant at this time of the season. It is possible that March weather coming after a very warm weather in February negatively impacted the pear psylla adult populations. Despite this unexpected phenomenon, the after petal fall management activities should start at the petal fall period and continue as the season progress.
Effective control of the first generation of the pear psylla will be very helpful for the final results of the seasonal pear psylla management practices. Application of products containing abamectin such as AgriMek, Agri-Flex, or various generic options (e.g., Abacus, Abba, EpiMek, Reaper or Zoro) plus 1 percent horticultural oil should still provide effective control of pear psylla. It is important to apply abamectin no later than within 10 days after petal fall when the young leaves intake of the product is the most efficient. With reported some instances of lower than expected efficacy of abamectin containing products, it is also very important to visually examine the foliage and shoots of pear trees and, if needed, follow up with another application of other insecticides such as Sivanto, Centaur or Beleaf. From products approved for organic pear production, multiple applications of Venerate XC provided effective control of pear psylla during our last year efficacy trials. Now is also the best timing to use kaolin clay (Surround) as the management tool against pear psylla.
Photo 2. Left to Right; Pear psylla adults, pear psylla nymph, and pear psylla eggs. Photos: G. Krawczyk
If the hand applied mating disruption materials such as Isomate, CheckMate or CideTrak products are planned for the control of OFM, CM, dogwood borer, peach tree borer or lesser peach tree borer, now is the optimal time to place MD dispensers in orchards. For the best control of the targeted pest(s), all mating disruption products should be placed in the orchard before the beginning of flight (biofix) for the intended pest to control. Positioning all MD dispensers as high as possible within the tree canopies will help to achieve the best control of targeted pests.
Photo 3. Left to Right; Hand applied mating disruption dipensers: Isomate CM/OFM TT dispenser, (Pacific BioControl Inc.), Cidetrak® OFM/CM MESO (TRECE Inc), and CheckMate OFM dispenser (Suterra, Inc.). Photos: G. Krawczyk